Differential response to benzylpenicillin in vivo of tolerant and non-tolerant variants of Streptococcus sanguis II.

Abstract

A variant that was highly tolerant to benzylpenicillin was obtained from a non-tolerant clinical isolate of Streptococcus sanguis II by repeated exposure to penicillin. The rabbit model of endocarditis was used to investigate the efficacy of a high dose regimen of benzylpenicillin (250 mg/kg; peak serum concentration c. 25 mg/l) in the prophylaxis and treatment of endocarditis during challenge or infection with the non-tolerant parent strain or its tolerant variant. The two strains exhibited a similar capacity to initiate infection. A single dose of penicillin administered 0.5 h before bacterial challenge protected six of nine rabbits infected with the non-tolerant parent strain, but none of nine infected with the tolerant variant. Treatment of established infection with penicillin administered twice daily for four days cured eight of 13 (61%) rabbits infected with the non-tolerant parent strain, but only one of 14 (7%) rabbits infected with the tolerant variant. These results support the view that tolerance to penicillin has therapeutic implications.

• Authors: J Meeson, A A McColm, P Acred, D Greenwood
• Journal: The Journal of antimicrobial chemotherapy (J Antimicrob Chemother) Vol. 25 Issue 1 Pg. 103-9 (Jan 1990) ISSN: 0305-7453 [Print] England
• PMID: 2318747 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Penicillin G

Topics

• Drug Tolerance
• Endocarditis, Bacterial (drug therapy)
• Genetic Variation
• Penicillin G (blood, pharmacology, therapeutic use)
• Streptococcal Infections (drug therapy)
• Streptococcus sanguis (drug effects, genetics)